Association between colorectal cancer and urologic cancers.

BACKGROUND Different types of urologic cancers have been associated with colorectal cancer (CRC) in hereditary nonpolyposis CRC, but it is still unknown whether there is an association between urologic cancer and CRC in the general population. We sought to quantify the risk for CRC after urologic cancer and the risk for urologic cancer after CRC in patients without known genetic syndromes. METHODS We performed a retrospective cohort analysis of the Surveillance, Epidemiology, and End Results program database from 1973 to 2000. Standard incidence ratios (SIRs) of observed to expected cases of invasive CRC were calculated for each urologic cancer site based on age, sex, ethnicity, and calendar year of diagnosis. Similar analysis was performed to determine the SIRs of urologic cancers in patients with previous CRC. RESULTS Overall, the risk for CRC was increased among patients with previous ureteral cancer (SIR, 1.80; 95% confidence interval [CI], 1.46-2.20) and renal pelvis cancer (SIR, 1.44; 95% CI, 1.20-1.72). This risk was greatest among patients who received the diagnosis of renal pelvis or ureteral cancer before the age of 60 years. There was a minimal increased risk for subsequent CRC in patients with bladder or renal parenchymal cancer. Overall, the risk for urologic cancer was increased after a diagnosis of CRC (SIR, 1.24; 95% CI, 1.20-1.28), with the highest risk for subsequent renal pelvis and ureteral cancers in patients with a CRC diagnosis before the ages of 50 to 60 years or multiple primary CRCs. CONCLUSIONS Previous renal pelvis and ureteral cancers, particularly when diagnosed at an early age, increase the risk for subsequent CRC. Likewise, a history of CRC, especially in cases with multiple primary tumors, is associated with an increased risk of renal pelvis and ureteral cancers. These findings support a possible common pathogenetic mechanism between CRC and urologic cancers and may have implications for screening guidelines.